1. Field
Aspects of embodiments of the present invention relate to a hollow fiber membrane module.
2. Description of the Related Art
A separation membrane is an instrument for separating materials according to a size of molecules or repulsive force between the molecules and the separation membrane, and drive force of separation is pressure, density, potential difference, and the like. When used in a separation process, the separation membrane has advantages in that process automation is convenient and phase change and high temperature processing are not required, and thus has been studied and used as a technology capable of replacing separation processes in environmental pollution prevention facilities or chemical industries. The separation membrane may include a reverse osmosis membrane, a nanofiltration membrane, an ultrafiltration membrane, a microfiltration membrane, an ion-exchange membrane, a gas separation membrane, a pervaporation membrane, and the like.
Hollow fiber membrane modules are classified into a pressurizing type and a submerged type depending on an operating method thereof. A pressurizing type filtration apparatus allows only fluid other than solids such as impurities, sludge, and the like to selectively permeate into a hollow through a surface of a hollow fiber membrane, by applying pressure to the fluid to be treated.
Although the pressurizing type filtration apparatus requires separate facilities for fluid circulation, it has an advantage in that the amount of permeated water per unit time is greater than the submerged type filtration apparatus due to high working pressure. In the submerged type filtration apparatus, the hollow fiber membrane is directly dipped into a tank containing a fluid to be treated, and negative pressure is applied to the interior of the hollow fiber membrane, thereby allowing only the fluid other than solids such as impurities, sludge, and the like to selectively permeate into the hollow through the surface of the hollow fiber membrane. Although the submerged type filtration apparatus provides a smaller amount of permeated water per unit surface area and per unit time than the pressurizing type filtration apparatus, the submerged type filtration apparatus has advantages in that facilities for fluid circulation are not required and raw water containing many pollutants can be directly treated.
Both the pressurizing type and submerged type filtration apparatuses may be divided into a both-end water collection type, in which permeated water flowing into the hollow through the hollow fiber membrane is collected at both ends of the hollow fiber membrane, and a single-end water collection type, in which permeated water is collected at one end thereof.
Such a hollow fiber membrane module includes a plurality of hollow fiber membranes or a bundle of hollow fiber membranes having a predetermined length. However, since the hollow fiber membranes have a long cylindrical shape, the submerged type module entails pressure drop in a longitudinal direction of the hollow fiber membranes even upon application of negative pressure thereto, and the pressurizing type module also entails pressure drop in the longitudinal direction of the hollow fiber membranes even in the case where raw water is pressurized and introduced into the hollow fiber membranes. Therefore, it is not easy to achieve uniform filtration in the longitudinal direction of the hollow fiber membranes.